OAKLAND, Calif., Feb. 21, 2014 /PRNewswire/ -- Women with low levels of an important protein known to bind to sex hormones prior to pregnancy were five times more likely to develop gestational diabetes than women with higher levels of the protein, according to a Kaiser Permanente study published today in the journal Diabetes Care.

"This study is among the first to find that low circulating levels of sex hormone binding globulin, measured years before pregnancy, are associated with increased risk of gestational diabetes," said Monique M. Hedderson, PhD, principal investigator of the study and research scientist with the Kaiser Permanente Division of Research in Oakland, Calif.

SHBG binds to the sex hormones, including testosterone and estrogen. It controls the amount of testosterone available in the body; lower SHBG levels are associated with higher testosterone levels. In women, higher testosterone is associated with insulin resistance, a risk factor for gestational diabetes. Levels of SHBG change dramatically, even during early pregnancy, in response to the hormonal changes.

For this study, the researchers retrospectively identified 256 women who developed gestational diabetes during pregnancy and 497 who did not. The women had given voluntary blood samples between 1985 and 1996 during routine care and subsequently delivered an infant in Kaiser Permanente's Northern California Region, on average six years later.

The researchers found that the risk of gestational diabetes increased as SHBG levels decreased, regardless of the woman's body mass index. However, researchers also found a strong association between high body mass index and an increased risk of developing gestational diabetes.

A previous report on the same cohort of mothers found that overweight women (BMI of 25 or greater) with low levels of the hormone adiponectin prior to pregnancy werenearly seven times more likely to develop gestational diabetes compared to normal weight women (BMI less than 25) with high levels of adiponectin.

This study included women who volunteered to participate in Kaiser Permanente's multiphasic health check-up exam, therefore the population may be more health conscious than the general population. However, the study cohort was diverse in terms of race-ethnicity and education levels.

Gestational diabetes, or glucose intolerance during pregnancy, has increased dramatically in recent decades and is now the most common complication of pregnancy, according to recent studies. It can lead to adverse outcomes, including larger-than-normal babies and subsequent delivery complications. Women with gestational diabetes are seven times more likely to develop type 2 diabetes later in life, and their children are at greater risk of becoming obese and developing diabetes themselves.

Kaiser Permanente can conduct transformational health research in part because it has the largest private patient-centered electronic health system in the world. The organization's electronic health record system, Kaiser Permanente HealthConnect®, securely connects 9.1 million patients to more than 16,000 physicians in almost 600 medical offices and 38 hospitals. It also connects Kaiser Permanente's research scientists to one of the most extensive collections of longitudinal medical data available, facilitating studies and important medical discoveries that shape the future of health and care delivery for patients and the medical community.

Research reported in this press release was supported in part by the National Institute of Child Health and Human Development of the National Institutes of Health under award number R01HD065904. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

About the Kaiser Permanente Division of ResearchThe Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR's 550-plus staff is working on more than 250 epidemiological and health services research projects. For more information, visit www.dor.kaiser.org or follow us @KPDOR.

About Kaiser PermanenteKaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America's leading health care providers and not-for-profit health plans. Founded in 1945, our mission is to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve approximately 9.1 million members in eight states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to kp.org/share.